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a finding that could one day aid the treatment of obesity and its opposite,
anorexia, scientists have found that worms and humans share about 150
genes involved in storing fat. Some of the genes identified in the study
were not previously known to play a role in body weight.

The researchers analyzed all 16,757 genes in the worm C. elegans,
whose genome has been sequenced. They identified about 400 that help regulate
how fat is stored and used. Next, they found that about 150 of these have
counterparts in humans.

"Our knowledge about how fat is regulated is still relatively limited,"
says Gary Ruvkun, a geneticist at Harvard Medical School in Boston, who
led the research. "These are early days still." He predicts
that only a fraction of the human genes implicated in this study may turn
out to be targets for treating obesity in people.

Jonathan M. Graff, a developmental biologist at the University of Texas
Southwestern Medical Center in Dallas, who studies fat genes in C.
elegans, calls the research "beautiful."

The work, he says, will help researchers identify the genetic underpinnings
of how fat cells are made, along with the proteins involved. Some of these
proteins may be excellent targets for drugs to help people with diabetes,
obesity and other conditions associated with the buildup of excess fat.

Ruvkun's team used a technique called RNA interference to identify genes
involved in regulating fat storage in the worm. The technique involves
giving the worm RNA molecules, which effectively silence one gene per
worm. For each 'silenced' gene, the researchers determined whether the
worm had more or less fat.

In one 'gene therapy' experiment, the researchers added fat-suppressing
genes to overweight worms, such as a mutant strain called 'tubby.' Roughly
70 of the genes cured every obese syndrome the researchers tested, according
to findings published in Nature.

The functions of many of the worm genes that Ruvkun studied have been
described previously. Some help cells create long fatty-acid molecules
or stitch together their fatty outer membranes, for example. Inhibiting
these genes should, and does, reduce fat storage.

However, the researchers say, they were surprised to find that when they
mutated a gene that burns fat, the worm seemed to store less fat. This
suggests that worms have a complex feedback system that researchers don't
yet understand, says Ruvkun.